The present invention relates to a semiconductor device and a method of producing the semiconductor device. In particular, the present invention relates to a semiconductor device having a double side electrode structure and a method of producing the semiconductor device.
Recently, in order to reduce a size of an electric device such as a cellular phone, a three-dimensional package technology has been developed to increase a mount density. Among the three-dimensional package technologies, a package-on-package (POP) technology, in which one package is laminated on another package, has been considered promising.
In the POP, a package having a double side electrode structure (a double side electrode package or a dual face package) has been used. In the double side electrode package, it is necessary to provide an inner wiring portion connected to a semiconductor chip; a through electrode for connecting an electrode on a package front surface and the inner wiring portion; and a through electrode for connecting an electrode on a package backside surface and the inner wiring portion.
A variety of double side electrode packages having various structures have been proposed. For example, Patent Reference 1 has disclosed a double side electrode package of a lead frame type. In the double side electrode package disclosed in Patent Reference 1, an inner lead with a step portion is used. A part of the inner lead is exposed from a resin sealing portion, and a front surface and a backside surface of the inner lead are used as outer electrodes. In the double side electrode package, the inner lead functions as a through electrode.
Patent Reference 2 has disclosed a double side electrode package of a ball grid array (BGA) type. In the double side electrode package disclosed in Patent Reference 2, a package substrate is provided with a step portion. An end portion of a wire bonding electrode is exposed from the step portion. A through electrode passes through the package substrate for connecting the end portion and an electrode on a front surface or a backside surface.
In order to mount elements with a high density using the double side electrode packages described above, it is necessary to reduce a thickness of each package. For example, in the double side electrode package disclosed in Patent Reference 1, the inner lead is provided with the step portion as a recess portion for accommodating a semiconductor chip, thereby reducing a thickness of the package. In the double side electrode package disclosed in Patent Reference 2, the package substrate is provided with the step portion. Further, the package substrate is mechanically ground from a backside surface thereof, thereby reducing a thickness of the package.
Patent Reference 3 has disclosed a double side electrode package of a resin sealing type. In the double side electrode package disclosed in Patent Reference 3, a through hole is formed in a sealing resin layer with a semiconductor chip sealed therein. The through hole is filled with a solder paste to form a through electrode for connecting an electrode on a front surface and an inner wiring portion. In the double side electrode package, the through electrode is formed in the sealing resin layer. Accordingly, it is not necessary to provide a recess portion in a package substrate.    Patent Reference 1: Japanese Patent Publication No. 2003-249604    Patent Reference 2: Japanese Patent Publication No. 2005-235824    Patent Reference 3: Japanese Patent Publication No. 2002-158312
In the double side electrode package disclosed in Patent Reference 3, it is necessary to accurately form the through hole in each package through laser radiation and the likes, thereby making a manufacturing process thereof complicated.
In view of the problems described above, an object of the present invention is to provide a semiconductor device and a method of producing the semiconductor device capable of solving the problems of the conventional semiconductor devices. In the method of producing the semiconductor device, it is possible to easily produce a double side electrode package without performing a complicated process such as forming the recess portion in the package substrate or forming a large number of the through holes through laser radiation.
Further objects and advantages of the invention will be apparent from the following description of the invention.